function z=dfunc1(w)
z=zeros(2,2);
x=w(1);
y=w(2);
z(1,1)=3*x^2-y^2;
z(1,2)=-2*x*y+3*y^2;
z(2,1)=sin(x*y)+x*y*cos(x*y);
z(2,2)=x^2*cos(x*y);